Lidia Esteve, Graduate Research Assistant Amy Kaleita, Assistant Professor Matthew Helmers, Assistant Professor Iowa State University Leaching of a Veterinary Antibiotic through Soil Columns

PATHWAYS OF ANTIBIOTIC MOVEMENT INTO THE ENVIRONMENT Sources and transport of pharmaceuticals in the environment Source: Heberer (2002), toxicology letters, 131, 5-17

ANTIBIOTICS IN THE ENVIRONMENT Manure from treated livestock is the most relevant source of veterinary antibiotic (Osenga, 2001). The major use of antibiotics in agriculture is as animal growth promoters (Levy, 1992). Scope of problem: USGS survey (2000).139 streams in 30 States were anayzed for 31 antibitotics. 17 antibiotics found at concentration 1.7 ppm (erythromycin)– 0.03 ppm (ciprofloxacin) Processes affecting antibiotic behavior and persistence:  Photodegradation  Sorption  Aerobic conditions  Abiotic hydrolisis  Biodegradation  Volatilization

PROBLEM STATEMENT Risks  Disturbance to environmental bacterial community  Development of bacteria resistance  Toxicity in plants Objectives of this study  Study of the leach of tylosin in manure  Get some preliminary data to understand the issue

MATERIALS AND METHODOLOGY 4 representative soils of Iowa :  Canisteo silty clay loam (507)  Clarion loam (138)  Sparta loamy fine sand (41)  Webster silty clay loam (107) Sigma® tylosin tartrate ( 50mg/kg manure) Swine Slurry manure (100ml/column) Indoor rainfall simulator (5cm/h intensity) “Enzime Linked Inmuno Sorbent Assay” ( ELISA) methodology

RESULTS 6 mg tylosin ml slurry manure in each column

RESULTS 60 mg+ 100 ml slurry manure in each column

CONCLUSIONS No significant concentration of tylosin (lower than 0.5 ng/ml) was found in the leachate from any kind of soil at neither 6mg tylosin/ column nor 60 mg tylosin/ column Tylosin likely remains in soil at our treatment concentrations, bound to the organic matter, clay or manure  Those results are in agreement with a recent Colorado University study (October 2004) where it was found that the antibiotic concentrations in river sediments are times higher than concentrations found in river water.

Concentrations found in tap water and distilled water suggest that :  There may be tylosin in tap water currently  There may be interactions with any compound in tap water The results in antibiotic detection show the need of more sensitive and reliable methodologies for antibiotic trace concentrations. Because ELISA methodology has shown in our study to be a screen method, HPLC methodology would be required for validation of the results. CONCLUSIONS

RECOMMENDATIONS AND SUGGESTIONS FOR FUTURE STUDIES Develop more analyses increasing the concentration of tylosin in order to find possible differences of tylosin concentration in leachate between different kind of soils Do extractions from soil with and without manure to determine what proportion of tylosin is bound to sediment and to the manure. More studies about the environmental repercussions of antibiotic accumulation in sediments are required.